The present invention relates to ink jet recording devices and, more particularly, to a system for detecting and identifying the presence of a specific type of printhead cartridge.
Ink jet recording devices eject ink onto a print medium such as paper in controlled patterns of closely spaced dots. To form color images, multiple groupings of ink jets are used, with each group being supplied with ink of a different color from an associated ink container.
Thermal ink jet printing systems use thermal energy selectively produced by resistors located in capillary filled ink channels near channel terminating nozzles or orifices to vaporize momentarily the ink and form bubbles on demand. Each temporary bubble expels an ink droplet and propels it toward a recording medium. Most commercial printing systems utilize a carriage type printer which has a relatively small printhead containing the ink channels and nozzles. The printhead is usually sealingly attached to an ink supply container and the combined printhead and container, referred to as a printhead cartridge, is reciprocated to print one swath of information at a time on a stationarily held recording medium, such as paper. After the swath is printed, the paper is stepped a distance equal to the height of the printed swath, so that the next printed swath will be contiguous therewith. The procedure is repeated until the entire page is printed.
An important practical concern for application of commercial thermal ink jet printers is to insure that a particular printhead cartridge assembly that is to be used is compatible with the function desired; i.e., if the printer is set to print in a first (red) color, that a red, rather than say black, cartridge assembly is installed. Alternatively, it may be required that a particular cartridge even though having a xe2x80x9ccorrectxe2x80x9d ink color is also the proper cartridge configuration for the specific system. For example, many commercial ink jet printers have OEM brand configurations and/or follow on products with perhaps, increased resolution, which may require a change in cartridge configuration and function. It is therefore desirable to identify that the second updated cartridge is being used rather than the earlier cartridge.
It is known in the prior art to provide encoding information on a printhead relating to a printhead characteristic such as color or serial number. U.S. Pat. No. 5,049,898 discloses encoded information in the form of a magnetic media which can be read by a magnetic read/write head to provide outputs for further use or display. U.S. Pat. No. 4,872,027 discloses a resistor circuit formed on a printhead in encoded form. The encoded information is addressed from a microprocessor which reconfigures control functions to provide different processing capabilities such as text or graphics. Co-pending application USSN 08/650,149discloses a printhead identification system in which a unique digital code is formed on a printhead, or group of printheads. Print operation is enabled when a matching code signal from a system controller to the printhead is confirmed. Co-pending application Ser. No. 08/572,595 filed on Dec. 14, 1995 and assigned to the same assignee as the present invention, discloses a system and method for sensing the presence or absence of an ink jet cartridge combined with an ink level sensing function.
Those prior art references relying on printhead cartridge code formation and detection techniques can be relatively expensive. It would be desirable to have a detection system which provides an elegant, yet simple, method for identifying a small number of possible printhead cartridge types.
It is therefore one object of invention to provide a printhead cartridge identification system which is adapted to include a relatively simple identification element associated therewith together with a single inexpensive sensing means for xe2x80x9creadingxe2x80x9d the identification element and producing an output signal representative of the specific type of printhead cartridge sensed. The cartridge signal is then used to prepare an ink jet printer for operation with the specific type of printhead cartridge identified.
In the present invention, and in an exemplary embodiment, a thermal ink jet printer is disclosed which includes a printhead cartridge for printing on a recording medium in response to image drive signals. Ink is supplied to a printhead from an ink container which is fluidly connected to the printhead. The printhead and container are mounted on a scanning carriage which moves back and forth across a print zone, the printhead ejecting ink droplets from nozzles to form an image on the recording medium. An optical system comprising a light source and a light detector is fixedly located along the path of travel of the carriage and positioned so that light from the light source is directed towards the ink container when it is positioned opposite the optical system. The ink container has an optical light directing element formed in a wall recess. Light from the light source is directed towards the light detecting element. In one embodiment, a cartridge reflector has a reflective surface whose reflective intensity varies according to the composition of a selected reflective material. Optical means include a light source for directing light towards the reflector and a sensor for sensing the intensity of the reflected light. Each level of detected intensity corresponds to a specific type of printhead cartridge with a predetermined set of printing characteristics.
According to a second embodiment of the invention, the relative location of the light source and light sensor of the optical assembly with respect to the cartridge reflector is set so that the reflected light from the light source is sensed only when a specific type of cartridge is in place.
More particularly, and in a first embodiment, the present invention relates to an ink jet printhead cartridge sensing system for identifying a specific type of cartridge, the sensing system comprising:
an optical assembly including a light source and a photosensor,
means for positioning a cartridge adjacent said optical assembly, said cartridge including at least one reflective member,
means for energizing said light source when said cartridge is adjacent said optical assembly, the light source emitting a beam of light which is directed generally towards said reflective member, said photosensor detecting the amount of light reflected from said reflective member and generating a signal indicative thereof and
cartridge identification means for processing the photosensor output signal and determining whether the signal corresponds to a predetermined signal representative of a specific type of cartridge.
The invention, in a second embodiment, relates to an ink jet printhead cartridge sensing system for identifying a specific type of cartridge, the sensing system comprising:
an optical assembly including a light source and a photosensor separated from each other by a set distance,
means for positioning said cartridge adjacent said optical assembly, said cartridge including at least one light reflective member comprising at least a first and second reflective member connected by a third surface,
meaning for energizing said light source when said cartridge is adjacent said optical assembly, the light source emitting a beam of light which is directed generally towards said reflective member and reflected therefrom towards said photosensor, said photosensor generating a high output when the separation distance between the light source and the photosensor is approximately equal to the length of the third surface connecting the first and second reflective surfaces and a low output signal when the separation distance and the third surface length are not approximately equal, and
cartridge identification means for processing the photosensor output signal and determining whether the signal corresponds to a predetermined signal representative of a specific type of cartridge.